Many simple Internet-facing web sites consist of a single host whose current domain (referred to as "@", or "$ORIGIN, in the zone file) is assigned the one A record for the domain, with subdomains like "www" assigned related CNAME records. For example, in the case of the "example.com" domain the DNS records might look like this:
@ IN A 1h 35.207.55.147
www IN CNAME 1h .example.com.
This approach might be impractical at home, where the roles played by any given machine may change over time, but the effort to re-IP some application services may not be worth the time.
For instance you may have a home file server named host1.example.com with an IP address of 10.0.0.100 that doubles as the primary home web server. In such a case one way to manage things would be to create two A records with the 10.0.0.100 address, one for the current domain and the other for host1. If host1's role ever changes all you'd need to do is assign a different IP address to the current domain.
Here's an example of what I'm talking about:
@ IN A 10.0.0.100
host1 IN A 10.0.0.100
www IN CNAME host1
If I ever decide to install a new web server to take the place of host1 (say, "host2"), all I'd need to do is assign the current domain to the IP of the new server and then change the CNAME record for www to point to that new host.